In general, a piston type compressor is equipped with a plurality of pistons, each of which reciprocates in accordance with the rotation of a rotary shaft. With the reciprocatory motion, refrigerant gas is sucked into a compressor and discharged outward after having compressed within the compressor.
Conventionally, a piston type compressor of this kind, as shown in FIG. 10, has a housing 52 in which a suction chamber 50 and a discharge chamber 51 are defined. A cylinder bore 53 is formed in a cylinder block 54. A valve plate 55 has a suction port 55a and a discharge port 55b formed therein. A suction plate 56 and a discharge plate 57 have a suction valve 56a and a discharge valve 57a, respectively. The valve plate 55 is disposed between the cylinder block 54 and the housing 52. The suction plate 56 and the discharge plate 57 are located on opposing sides of the valve plate 55.
As a rotary shaft 60 rotates, with a piston 58 moving leftward, as illustrated in FIG. 10, the suction valve 56a is elastically deformed to open the suction port 55a, in order to allow the refrigerant gas in the suction chamber 50 to be sucked, via the suction port 55a, into a working chamber 59 in the associated cylinder bore 53. When the piston 58 shifts rightward after the suction operation is completed, the suction valve 56a closes the suction port 55a. Thereafter, when the pressure in the working chamber 59 rises to, or above a predetermined level, the discharge valve 57a elastically deforms to open the discharge port 55b, in order to discharge the compressed refrigerant gas from the working chamber 59 into the discharge chamber 51, via the discharge port 55b.
A lubricant oil is generally mixed with the refrigerant gas, which will stick on the suction valve 56a, etc. Consequently, when the suction valve 56a elastically deforms to open the suction port 55a, the oil might cause the suction valve 56a to adhere to the suction port 55a, thus adversely affecting the suction response.
The suction valve is designed to open the suction port against the elasticity of the valve in accordance with a change in the suction pressure of the refrigerant gas. This design requires that the pressure of the refrigerant gas be raised above the elastic force of the suction valve, thus resulting in an increase of the pressure loss in the compressor.
In addition, since the suction chamber adjoins the discharge chamber, the heat of the gas with a high temperature within the discharge chamber expands the refrigerant gas in the suction chamber. Decrease in density of the refrigerant gas before entering the working chamber leads to substantial drop in compression volume in the working chamber to cause volumetric efficiency of the compression to be reduced.
Accordingly, the present invention has been accomplished with a view to overcoming the above-described problems, and it is an object of the invention to provide a refrigerant gas guiding mechanism for a piston type compressor with an efficient sealing, which can suppress the pressure loss resulting from the structure of the suction valve, and improve volumetric efficiency.